Mechanism of lime decomposing Al2O3-containing fayalite melt

A method to upgrade the iron grade in copper slag was proposed using lime to decompose Al 2 O 3 -containing fayalite melt (AFMT). Thermodynamic calculations indicated that adjusting the CaO/AFMT ratio can yield a residual melt with a FeO concentration of 75-88 wt.% and produce Ca 2 SiO 4 . In-situ observations suggested that the reaction was impeded in some way. Quenching experiments revealed that the initial reaction products consisted of calcium ferrite compounds and FeO-CaO melt. At the FeO-CaO melt/AFMT interface, Ca 2 SiO 4 particles precipitated, forming a dense Ca 2 SiO 4 film that significantly impeded mass transfer. Although trace amounts of Al 2 O 3 in AFMT temporarily enhanced mass transfer, they were insufficient to overcome this retardation effect. The decomposition reaction was far from achieving equilibrium, demonstrating a self-retardation effect. Measures must be implemented to eliminate this self-retardation effect and enhance the efficiency of reaction kinetics.